Claims
- 1. A diesel engine system comprising a diesel engine including engine cylinders, an engine management unit and an exhaust system, said exhaust system incorporating a catalyst effective to convert NO to NO2 under normal operating conditions, a carbonaceous particulate trap mounted downstream of the catalyst and adapted to oxidize particulates, an exhaust gas recirculation valve for recirculating a portion of the exhaust gases to said engine cylinders wherein said valve is controlled by said engine management unit and the exhaust gases have a volume, and means for cooling the recirculated exhaust gases wherein said means for cooling is mounted between said trap and said valve, wherein said valve is mounted completely downstream of said means for cooling such that the recirculated exhaust gases are cooled by said means for cooling to a temperature of about 80° C. to about 150° C. before the recirculated exhaust gases pass over said valve.
- 2. A system according to claim 1, wherein the exhaust gas recirculation valve is adjustable to recirculate between 5 to 30 percent by volume according to the position of the valve.
- 3. A system according to claim 1, wherein a pump is incorporated between the exhaust gas recirculation valve and the engine cylinders, wherein the pump is controlled by the engine management unit.
- 4. A system according to claim 1, wherein the diesel engine is a heavy duty diesel engine.
- 5. A system according to claim 1, wherein said trap is adapted to oxidize particulates by combusting the particulates with at least the NO2 converted from the NO by said catalyst.
- 6. A process for controlling the amount of NOx in diesel engine tailpipe exhaust gases, the process comprising the steps of: converting at least a portion of NO in the engine exhaust gases to NO2 by passing the engine exhaust gases over a catalyst; trapping at least a majority of carbonaceous particulates in the engine exhaust gases with a trap; continuously oxidizing the particulates; cooling the cleaned engine exhaust gases leaving the trap to a temperature of about 80° C. to about 150° C.; and recirculating at least a portion of the cooled exhaust gases to the engine cylinders using an exhaust gas recirculation valve.
- 7. A process according to claim 6, wherein the quantity of cleaned engine exhaust gases recirculated is in the range 5 to 30 percent by volume.
- 8. A process according to claim 6, wherein the step of oxidizing the particulates comprises combusting the particulates with at least the NO2 converted from the NO by the catalyst.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9717034 |
Aug 1997 |
GB |
|
Parent Case Info
This application is the U.S. national-phase application of PCT International Application No. PCT/GB98/02408.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/GB98/02408 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO99/09307 |
2/25/1999 |
WO |
A |
US Referenced Citations (13)
Foreign Referenced Citations (2)
Number |
Date |
Country |
8338320 |
Dec 1996 |
JP |
9088727 |
Mar 1997 |
JP |
Non-Patent Literature Citations (2)
Entry |
UK Search Report, dated Nov. 5, 1997, for corresponding GB application. |
International Search Report, dated Nov. 26, 1998; for corresponding EPO application. |